4) (3+2y)/y^4 : (2/3 + 1/y).

4) $$\frac{3+2y}{y^4} : (\frac{2}{3} + \frac{1}{y}) = \frac{3+2y}{y^4} : \frac{2y+3}{3y} = \frac{3+2y}{y^4} \cdot \frac{3y}{2y+3} = \frac{(3+2y)3y}{y^4(2y+3)} = \frac{3}{y^3}$$.

Ответ: $$\frac{3}{y^3}$$